Commutator



Sept 15, 1941 R. G. MccUsKER 2,256,321v

COMMUTATOR Filed July 5, 1940 Patented Sept. 16, 1941 UNITED STATES PATENT OFFICE Heinze Electric Cor poration, Lowell, Mass., a

corporation of Michigan Application July 5, 1940, Serial No. 344,043 11 Claims. (Cl. 171-321) The present invention relates to commutators of dynamos and to a method of making the same.

It is an important object of this invention to provide a novel construction in a commutator for small motors and the like whereby such commutators may be inexpensively formed to provide a rigid structure adequate to meet the conditions imposed by temperature, voltage, and centrifugal force in small dynamos.

It is also an important object of this invention to provide a novel method of making commutators for small motors and the like.

Other and further important objects of this invention will be apparent from the disclosures in the specification and the accompanying drawing, in which:

Figure 1 is a plan view of a strip of metal to be bent and cut to define a commutator for dynamos;

Figure 2 is a top View showing of the strip of Figure 1 bent to deiine a cylinder;

Figure 3 is a sectional side View of the cylinder of Figure 2 along lines II-II;

Figure 4 is a side View of a commutator formed from the strip of Figure l;

Figure 5 is a sectional View of the commutator of Figure 4;

Figures 5, '7, and 8 are plan Views of strips of metal to show modifications in the slot shape;

Figure 9 is a view in elevation of a metal strip bent into a cylinder and showing a modification in slot shape;

Figure 10 is a view in elevation of the cylinder of Figure 9 lled with a plastic and shaped to define a commutator; and

Figure l1 is a sectional View of the commutator of Figure l0.

In one form of commutator made according to this invention, a strip of metal, indicated generally by the numerals ID, is shaped to provide a body portion II, from which there extends longitudinally spaced soldering lugs I2 and longitudinally spaced fingers I4. The strip is apertured, as indicated at I3, the center of the apertures or holes being substantially in line with the upper edge of the body portion (see Figure l).

The strip Iii is bent so that its body portion defines a cylinder I5 with outwardly bent lugs I2, and with the ngers I4 bent inwardly to deiine hooks I 5, as shown in Figures 2 and 3. A length of fish line il is wrapped about the upper end of the cylinder and crossing the apertures,

as best indicated in Figure 9, so that a plastic the iish line insulating material forced under high pressure into the mold of Figure 2 will emerge through the apertures I3 and envelop the nsh line Il, as indicated at ZI in Figures 5 and 6.

Similar numerals indicate similar parts in the gures.

After the strip II] has been formed into the cylindrical form of Figure 2, the cylinder is placed in a suitable support, a mandrel is placed in the center of the cylinder, plastic insulating material I8 is forced under high pressure into the cylinder, and themandrel is withdrawn to define the bore for the armature shaft as indicated at 23 in Figure 5. The plastic material is squeezed through the apertures I3 to envelop I'I and form an external bead 2|, and this plastic material extends above the body portion of the strip and, with the bead, forms a substantially T-shaped bead at one end of the commutator as indicated at I 9 in Figure 4. The shape of the containing support for the filling operation is such that there is a layer oi plastic at the bottom of the commutator at the end of the filling operation, and this is indicated at 23 in Figure 4.

It will now be evident that at the end of the illing operation we have an assembly which presents a body portion surmounted by a cap I9 of the plastic integral with the bead 2l, and a bottom layer 28 of plastic, and With the hooks i6 rmly embedded in the plastic. The next operation is that of milling or sawing the body portion of the strip to now define a cylindrical commutator of a plurality of peripherally spaced segments 22, separated from each other in insulated relation to each other by slots 23, and each having its soldering lug I2 to which the leads of armature coils may be soldered.

Figures 1 to 5, inclusive, show the evolution of the commutator from the blank or strip of Figure 1 to the finished cylindrical commutator shown in section in Figure 5.

rThe contour of the cap portion of the commutator, which includes the bead, and the shape g of the lock formed between the plastic and the lug end of the commutator segment may be modified.

In Figure 6 there is shown a portion of a strip I0 with its body portion II, its iingers I4, and its soldering lugs I2. Slots 24 begin in the body portion II and extend into the soldering lugs I2, with substantially half of the length of the slot being in the body portion.

In another modiiication, shown in Figure 7, slots 25 begin in the body portion II and extend into the soldering lugs I2, with the greater portion of the slot being in the lug.

In another modication, shown in Figure 8, triangular openings 26 are formed in the soldering lugs l2 and with the base of the triangle being disposed slightly below the upper edge of the body portion Il.

In another modiiication, shown in Figures 9, l0, and 11, the soldering lugs l2 are provided with relatively wide and deep slots 21 so that a lead wire 2S, as indicated in Figure 10, may be entered in the slot and be bent for soldering to the lugs. A portion of the slot opening appears above the plastic as shown in Figures l and il. The slots begin in the body portion as indicated at 3i) in Figure 9, and the major portion of the slot is in the lug I2.

The steps of bending the strip to cylindrical form, filling this cylinder with an insulating material of a plastic which iiows outwardly of the strip to form an external bead, and then sawing the strip to provide a cylindrical commutator of peripherally spaced segments, are common to all forms of the strip, so that each segment has its soldering lug at one end and its embedded linger at the other end.

The iish line l'l is a string of strong, librous material, and provides an inexpensive and easily applied reinforcing element extending longitudinally of the bead 2l. Other materials may be used to provide the longitudinally extending reinforcing element, but lish line has been proved useful because inexpensive, and because Ythe hot plastic nds its way about the strands oi' the string during the molding operation.

The bead is usually severed during the cutting operation to define the segments because the cutting saw runs through the bead as it finishes its cutting stroke to separate the segments in forming the slot 23.

While I have shown several embodiments of my invention, it will, of course, be understood that I do not wish to be limited thereto, since many modications may be made, and I therefore contemplate by the appended claims to cover all such modilications as fall within the true spirit and scope of my invention.

I claim as my invention:

1. A commutator assembly formed of a plurality of peripherally spaced commutator segments held in assembled relation to each other by a molded body of insulating material, each of said segments comprising a body portion having an inturned finger at one end embedded in said insulating material and an outturned linger at the other end, said insulatingr material extending into engagement with opposed surfaces of said outturned linger, thereby to hold said segment firmly in place on said molded body of insulating material.

2. A commutator assembly formed of a piurality of peripherally spaced commutator segments held in assembled relation to each other by a molded body of insulating material, each of said segments comprising a body portion having an inturned linger at one end embedded in said insulating material and an outturned finger at the other end, said outturned finger having an opening therethrough, said insulating material extending through said opening in said outturned finger and into binding engagement with the outer surface of said outturned finger.

3. A commutator assembly formed of a plurality of peripherally spaced commutator segments held in assembled relation to each other by a molded body of insulating material, each of said segments comprising a body portion having an inturned linger at one end embedded in said insulating material and an outturned linger at the other end having an opening therethrough, said insulating material having an integral T- head lock extending through the opening in said outturned linger, with the T-head portion of said lock on the opposite side of said outturned linger from the main body portion ci said insulating material.

4i. A commutator formed of a strip of metal shaped to deline an elongated body portion, longitudinally spaced and outstanding soldering lugs along one longitudinal margin of the body, and longitudinally spaced and outstanding bent iingers along an opposite margin of the body, means defining apertures in said soldering lugs and eX- tending into said body portion, said strip being bent to delhie a cylinder having inwardly bent fingers, a filling or" an insulating plastic in said cylinder and extending outwardly through the apertures to form an integrally united assembly, said body portion of said cylindrically formed strip being cut to deline a plurality of peripherally spaced commutator segments in insulated relation to each other and with each segment having a soldering lug and an embedded nger.

5. A commutator assembly formed of a plurailty of peripherally spaced commutator segmerits held in assembled relation to each other by a molded body of insulating plastic, each of said segments comprising a body portion having an apertured soldering lug at one end and having an inwardly bent linger at the other end with the linger embedded in said body of plastic and an outwardly extending head of said plastic about said assembly and having connecting portions extending through said apertures to integrally connect said head with saidbody of plastic.

6. A commutator assembly formed of a plurality of peripherally spaced commutator segments held in assembled relation to each other by a molded body of insulating plastic to define a cylinder having an internal filling of the plastic, each of said segments comprising a body portion having an apertured soldering lug at one end and having an inwardly bent linger at the other end with the linger embedded in the plastic filling, said lling being arranged extending through said apertures to define an outstanding bead, and a longitudinally extending reinforcement of fibrous material disposed in said bead.

7. A commutator assembly formed of a plurality of peripherally spaced commutator segments held in assembled relation to each other by a molded body of insulating plastic to define a cylinder having an internal lilling of the plastic, each of said segments comprising a body portion having an apertured soldering lug at one end and having an inwardly bent finger at the other end with the linger embedded in the plastic iilling, said filling being arranged extending internally above the body portion of the segment and externally through the apertures in said lugs to define a substantially T-shaped bead of plastic.

8. A commutator assembly formed of a plurality of peripherally spaced commutator segments held in assembled relation to each other by a molded body of insulating plastic to define a cylinder having an internal filling of the plastic, each of said segments comprising a body portion having an apertured soldering lug at one end and having an inwardly bent nger at the other end with the finger embedded in the plastic filling, an externally disposed reinforcing element Wrapped about said assembly and crossing said apertures, said filling being arranged extending through said apertures and about said reinforcing element to provide an external bead.

9. A commutator assembly formed of a plurality of peripherally spaced commutator segments held in assembled relation to each other by a molded body of insulating plastic to define a cylinder having an internal filling of the plastic, each of said segments comprising a body portion having a bent finger at one end with the nger embedded inthe plastic, and having a soldering lug at the other end provided with a slot extending into the body portion, an externally disposed reinforcing element disposed about said assembly and crossing said slots, said filling being arranged extending through said slots and about said reinforcing element to provide an external bead.

10. A commutator assembly formed of a pluralty of peripherally spaced commutator segments held in assembled relation to each other by a molded body of insulating plastic to dene a cylinder having an internal filling of the plastic, each of said segments comprising a body portion having an inwardly bent finger at the other end with the finger embedded in the plastic, an externally disposed reinforcing element disposed about said assembly and adjacent the one end of the segment, said filling being arranged extending outwardly of said segments and about said reinforcing element to provide an external bead.

11. In combination, a central body of an insulating plastic, a plurality of peripherally spaced segments disposed about said central body to define a commutator, means on said segments embedded in said central body, elongated beads of insulating plastic engaging the external faces of said segments and formed integral with said central body, and longitudinally extending reinforcing means in said beads.

RAYMOND G. MCCUSKER. 

